If I go to the end of a line in the IDE Editor e.g. line is 'end mouseUp' and press return then 'end mouseUp' changes to 'nd mouseUp'

in other words the first char of the previous line is removed. Its easy to add the 'e' back but it is a reproducable minor bug. I'm on OSX El Capitan. Is anyone else seeing this? If so I'll raise a bug report.